There are several known methods that can be used to provide localization data on surface targets. For example, a surface movement radar (SMR) will provide detection of all surface targets on the movement area of an airport. The radar technology used in an SMR is based on the transmission and reception of radio waves and reception of return echoes from all of the targets. A combination of the narrow beam antenna and highly precise measurement of the delay between transmission and reception allows an SMR to provide highly accurate position information on all of the detected targets. An SMR is called a non-cooperative sensor, because it does not require any cooperation from the target and will provide data on all the targets without any special equipment on the targets. This is one of the significant advantages of SMR, because some targets may be unwilling to cooperate in target detection.
Another method used to provide localization data on targets in a cooperative sense uses the signal generated from existing aircraft transponders, such as radio beacons, that most aircraft are mandated to carry. One example of this method used by secondary surveillance radars employs a ground station transceiver to interrogate an aircraft's Air Traffic Control Radar Beacon System (ATCRBS) or Mode S transponder and receive reply signals from the aircraft system. Another example of a cooperative method is the Automatic Dependent Surveillance-Broadcast (ADS-B) system, which listens to transponder initiated Mode S transmissions, or squits. Using either of these methods the ground station decodes information contained in the reply signals to determine the target's identity, call sign, altitude, code and/or mode, thereby uniquely identifying the aircraft. In addition, current ground transceivers, such as beacon sensors, can also perform highly accurate target localization using multilateration or similar methods.
A multilateration system provides good positional data as well as identification data providing an easier capability of accessing flight plan and other databases of related information. However, as an advanced surface movement and guidance control system (ASMGCS), a beacon sensor-based surface multilateration system requires the installation of multiple receivers and at least one transmitter scattered about the airport surface on carefully surveyed points, the installation of electrical power, communication links to a central processor and system optimization, and may also require installation of new access roads or improvement of existing access roads to service these sites. All of the aforementioned requirements drive up the cost of obtaining and maintaining an ASMGCS multilateration system.
Since an ASMGCS radar system will provide position data on all surface targets, not just transponder-equipped surface targets, many airports are opting to install ASMGCS radar equipment. While an ASMGCS radar system provides position data on all targets, an ASMGCS radar system does not provide any target identification data to facilitate interpretation of the surface movement picture and does not provide easy access to flight plan and other relevant data.
What is needed is a system that is less expensive than installing and maintaining a complete multilateration system that can augment the target position data from a radar system with the identification data that is available from a traditional multilateration system and thus provide easy access to flight plan and other data. The present invention provides such a system and method, both of which augment radar data with target identification data that is provided by one or more beacon transceivers.